Turbines are generally designed as radial compressors or as side channel compressors. Radial compressors are used primarily for generating high-volume flows, and side channel compressors for generating high pressure differentials.
DE 31 28 374 A1, teaches a side channel pump supported by radial blades and usable for gaseous media, with the rotor having radial blades bent convex at one end, said blades urging the medium being transported into a circumferential channel that expands helically, from which the transported medium is conducted into a side channel pump whose radially directed chamber blades are mounted either on the side of the rotor opposite the radial blades or, on the outer circumference of the rotor. The medium, transported outward therein by the radial blades, is conducted over a relatively long distance with multiple deflections to the side channel, considerably reducing its efficiency.
DD-PS 4862 teaches a multistage turbine according to the species, but designed for liquid media in that publication, with the first stage designed as a radial compressor whose radial blades gradually merge with the chamber blades of the second stage, designed as a side channel compressor. The chambers of the side channel compressor surrounding the radial blades are open on the side facing the radial blades, so that the medium being transported enters the chambers of the side channel compressor directly from the flow channels of the radial compressor. However, the chamber blades are aligned radially, and the radial blades, curved only slightly concavely, make a direct transition to the chamber blades. Consequently, a pressure that develops in the side channel chambers results in backpressure that is unimpeded and directed radially inward into the flow channels of the radial compressor, limiting the efficiency that can be attained.
In addition, DD-PS 35 450 teaches a self-priming liquid centrifugal pump, whose rotor is provided in its central area with convexly curved radial blades and in its circumferential area with convexly bent chamber blades. The radial blades run inside a cylindrical housing intermediate jacket, interrupted at only one point over an arc of about 60.degree., so that the liquid flow can make the transmission from the radial pump to the circumferential channel which has chamber blades only at this interruption. Since the spacing of the radial blades and chamber blades is equal to at least the thickness of the housing intermediate jacket, considerable turbulence occurs at the transition, considerably limiting the efficiency that can be attained.
DD-PS 41 513 teaches a combined rotor for pumps, compressors, or the like with curved radial blades that convey the medium centrally into a circumferential channel fitted on two opposite sides with straight chamber blades directed radially. The medium flow generated by the radial blades is broken up at the outer circumferential wall of the circumferential channel and deflected toward the chamber blades, so that two circular flows directed in opposite directions develop in the circumferential channel and impact the medium flow generated by the radial blades. Since this medium flow abruptly loses the guidance provided by the radial blades upon entering the circumferential channel, considerable turbulence and rapid backpressure develop, so that only very limited efficiency can be attained with this known device.